Modern telecommunication systems provide a solid coverage area particularly in densely populated areas. However, any environment may include locations where the quality of a radio communication link between a serving base station and a terminal device communicating with the base station is poor because of buildings and/or other obstacles between the base station and the terminal device. When the terminal device enters such a location, the quality of the radio communication link drops suddenly, and the probability of disconnection increases. This is particularly annoying when a user of the terminal device is conducting a telephone call or is having another ongoing conversational or streaming connection, i.e. the terminal device is in a connected state. When the quality of the radio communication link drops below a tolerable level in the connected state, the terminal device may have to go to idle state and attempt a reconnection with the serving (or another) base station. In any case, the connection is lost.
When the drop in the quality of the radio communication link is slow, a cellular network can prepare for the drop by handing the terminal device over to another base station. However, there are several cases where the drop is so sudden that the serving base station does not have time to issue a handover command and, as a consequence, the call is dropped. Such may happen when a terminal device is served by an indoor base station and the user of the terminal device exits the building. As another example, the user may be travelling on a train equipped with a mobile (or nomadic) relay base station relaying connections between terminal devices in the train and the cellular network. When the user exits the train and the train doors close, the connection is suddenly lost.